The present inventive concept generally relates to the field of electronics and, more particularly, relates to wafer bonding.
In a semiconductor device manufacturing process, a wafer bonding process for bonding two wafers to each other may be performed. Such a wafer bonding process may be performed to improve the mounting density of a chip in a semiconductor device. For example, a semiconductor module having a structure in which chips are stacked may be advantageous for reducing lengths of wires between chips, for high-speed signal processing, and for improving the mounting density of the chips. In the case of manufacturing a semiconductor module having a stacked chip structure, it may be more productive to bond wafers and separate the wafers into stacked chip units than to bond chips. A wafer bonding process may be performed to facilitate handling of a device wafer by bonding the device wafer to a carrier wafer. The wafer bonding process may be performed by using a direct bonding method in which two wafers are directly bonded without a separate medium. The direct bonding methods may be typically performed by using a wafer bonding apparatus having supporting plates on which substrates are placed and fixed and a pressing device to press the substrates.